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Witte JF, Wasternack J, Wei S, Schalley CA, Paulus B. The Interplay of Weakly Coordinating Anions and the Mechanical Bond: A Systematic Study of the Explicit Influence of Counterions on the Properties of (Pseudo)rotaxanes. Molecules 2023; 28:molecules28073077. [PMID: 37049840 PMCID: PMC10096450 DOI: 10.3390/molecules28073077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 03/17/2023] [Accepted: 03/27/2023] [Indexed: 04/03/2023] Open
Abstract
Weakly coordinating anions (WCAs) have attracted much attention in recent years due to their ability to stabilise highly reactive cations. It may well be argued, however, that a profound understanding of what truly defines a WCA is still lacking, and systematic studies to unravel counterion effects are scarce. In this work, we investigate a supramolecular pseudorotaxane formation reaction, subject to a selection of anions, ranging from strongly to weakly coordinating, which not only aids in fostering our knowledge about anion coordination properties, but also provides valuable theoretical insight into the nature of the mechanical bond. We employ state-of-the-art DFT-based methods and tools, combined with isothermal calorimetry and 1H NMR experiments, to compute anion-dependent Gibbs free association energies ΔGa, as well as to evaluate intermolecular interactions. We find correlations between ΔGa and the anions’ solvation energies, which are exploited to calculate physico-chemical reaction parameters in the context of coordinating anions. Furthermore, we show that the binding situation within the (pseudo)rotaxanes can be mostly understood by straight-forward electrostatic considerations. However, quantum-chemical effects such as dispersion and charge-transfer interactions become more and more relevant when WCAs are employed.
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Affiliation(s)
- J. Felix Witte
- Institut für Chemie und Biochemie, Physikalische und Theoretische Chemie, Freie Universität Berlin, Arnimallee 22, 14195 Berlin, Germany
- Correspondence: (J.F.W.); (B.P.)
| | - Janos Wasternack
- Institut für Chemie und Biochemie, Organische Chemie, Freie Universität Berlin, Arnimallee 20, 14195 Berlin, Germany
| | - Shenquan Wei
- Institut für Chemie und Biochemie, Physikalische und Theoretische Chemie, Freie Universität Berlin, Arnimallee 22, 14195 Berlin, Germany
| | - Christoph A. Schalley
- Institut für Chemie und Biochemie, Organische Chemie, Freie Universität Berlin, Arnimallee 20, 14195 Berlin, Germany
| | - Beate Paulus
- Institut für Chemie und Biochemie, Physikalische und Theoretische Chemie, Freie Universität Berlin, Arnimallee 22, 14195 Berlin, Germany
- Correspondence: (J.F.W.); (B.P.)
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Koutsoukos S, Philippi F, Rauber D, Pugh D, Kay CWM, Welton T. Effect of the cation structure on the properties of homobaric imidazolium ionic liquids. Phys Chem Chem Phys 2022; 24:6453-6468. [PMID: 35244651 DOI: 10.1039/d1cp05169e] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
In this work we investigate the structure-property relationships in a series of alkylimidazolium ionic liquids with almost identical molecular weight. Using a combination of theoretical calculations and experimental measurements, we have shown that re-arranging the alkyl side chain or adding functional groups results in quite distinct features in the resultant ILs. The synthesised ILs, although structurally very similar, cover a wide spectrum of properties ranging from highly fluid, glass forming liquids to high melting point crystalline salts. Theoretical ab initio calculations provide insight on minimum energy orientations for the cations, which then are compared to experimental X-ray crystallography measurements to extract information on hydrogen bonding and to verify our understanding of the studied structures. Molecular dynamics simulations of the simplest (core) ionic liquids are used in order to help us interpret our experimental results and understand better why methylation of C2 position of the imidazolium ring results in ILs with such different properties compared to their non-methylated analogues.
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Affiliation(s)
- Spyridon Koutsoukos
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, White City Campus, London W12 0BZ, UK.
| | - Frederik Philippi
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, White City Campus, London W12 0BZ, UK.
| | - Daniel Rauber
- Department of Chemistry, Saarland University, Campus B2.2, 66123, Saarbrücken, Germany
| | - David Pugh
- Department of Chemistry, Britannia House, Kings College London, 7 Trinity Street, London SE1 1DB, UK
| | - Christopher W M Kay
- Department of Chemistry, Saarland University, Campus B2.2, 66123, Saarbrücken, Germany.,London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London WC1H 0AH, UK
| | - Tom Welton
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, White City Campus, London W12 0BZ, UK.
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Noorhisham NA, Amri D, Mohamed AH, Yahaya N, Ahmad NM, Mohamad S, Kamaruzaman S, Osman H. Characterisation techniques for analysis of imidazolium-based ionic liquids and application in polymer preparation: A review. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.115340] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Haddad B, Paolone A, Villemin D, Lohier JF, Drai M, Bresson S, Abbas O, Belarbi EH. para‑Xylyl bis‑1‑methylimidazolium bis(trifluoromethanesulfonyl)imide: Synthesis, crystal structure, thermal stability, vibrational studies. J Mol Liq 2018. [DOI: 10.1016/j.molliq.2018.03.113] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Panda S, Kundu K, Umapathy S, Gardas RL. A Combined Experimental and Theoretical Approach to Understand the Structure and Properties ofN-Methylpyrrolidone-Based Protic Ionic Liquids. Chemphyschem 2017; 18:3416-3428. [DOI: 10.1002/cphc.201700886] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 09/17/2017] [Indexed: 12/23/2022]
Affiliation(s)
- Somenath Panda
- Department of Chemistry; Indian Institute of Technology Madras; Chennai 600036 India
| | - Kaushik Kundu
- Department of Inorganic and Physical Chemistry; Indian Institute of Science; Bangalore 560012 India
| | - Siva Umapathy
- Department of Inorganic and Physical Chemistry; Indian Institute of Science; Bangalore 560012 India
| | - Ramesh L. Gardas
- Department of Chemistry; Indian Institute of Technology Madras; Chennai 600036 India
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